The prior art displays known to the present inventors typically involved an attitude director indicator (ADI) where, among other details, information is provided as to the roll of an airplane and its degree of climb or descent with respect to level. Typically, there are warning indicators when the rate of descent or climb is nearing and/or exceeding preset values. A separate horizontal situation indicator (HSI) typically provides, among other details, heading information and shows the craft's heading with respect to some North reference such as true North or magnetic North.
Since it is normally desirable to reduce the number of required display surfaces in an airplane, and since a pilot must perform a certain amount of mental integration to combine the information from two separately situated displays, the inventors have provided the present approach to a display which uses electronics to integrate the presentation to the pilot or other viewer. Although left out of the drawings for clarity of presentation, other non-attitude and heading cues normally found on present day ADI's and HSI's are considered to be a part of the present inventive concept presentation capability even though not specifically recited herein. Lateral image disparity cues are used to stimulate a depth sense (stereopsis) in the viewer so that this large amount of information can be presented spacially distinct and relevant form. The observer perceives depth in the display and thus, senses that certain objects are in front of or behind other objects. Without stereopsis, this presentation would be overly cluttered and difficult to interpret.
The stereopsis may be produced by any of several well-known means. One approach is disclosed in the present application wherein alternating left and right eye perspective views, images or pictures of a 3D situation are presented on a CRT screen. The concept uses switching LCD glasses or lenses to unmask the appropriate view to each eye in turn. In other words, the left eye sees only left eye images and the right eye sees only right eye images.
In concept, the aircraft symbol is visualized as lying at the center of a spherical grid with roll, pitch and heading scales displayed in conjunction with the sphere. For clarity of presentation and similarity to existing aircraft instruments, the aircraft symbol and roll scale are locked in a plane parallel to the display surface. A roll pointer is also located on the display's surface plane. This pointer tracks the intersection of the pitch scale with a display surface as the pitch scale moves in conjunction with roll and pitch movements during aircraft maneuvers. The nose of the 3D aircraft symbol always points to the current pitch value.
In the embodiment shown, the pitch and roll rotation axes are orthogonal. Similarly, the pitch and heading rotation axes are orthogonal to each other although heading is not orthogonal to roll. Current heading value is indicated by the intersection of the pitch scale with the heading scale.
If the viewpoint of the observer is placed to look directly along the longitudinal axis of the 3D aircraft symbol, this instrument presentation is very similar to a conventional attitude director indicator. The surface of the sphere is represented by a fine mesh or grid colored blue above the horizon line (sky) and brown below the horizon line (earth). However, unlike a conventional attitude director indicator, heading indication is added, and the heading scale appears curved when a pitch angle is applied. Generally speaking, however, the display may be regarded as an extension of a conventional attitude director indicator directly into three dimensional information as far as the pilot of the aircraft is concerned.
Once the sphere is visualized with the aircraft at the center, situational awareness cues can be added to the display, showing a complete global view of military threats, or civilian traffic environment. A vector drawn from the viewer's aircraft to a threat in the real world can be visualized in the display domain as a vector from the aircraft symbol to the three dimensional representation of the threat. A window drawn around where that vector pierces the display sphere would then frame the relative polar coordinate angle of that threat. Color coding of the window can also be used wherein, as an example, red may be used for threats, green for friendly craft, and yellow for unknowns.
Like a conventional attitude director indicator, this format is an inside out presentation. It presents pictorially what the pilot would see looking out the window of the aircraft. Once the cue window appears on the sphere, the observer has an instantaneous sense of the real world direction from his aircraft to the threat. For example, if sensors or data linked information reveals a threat above, behind and to the left of the viewer's aircraft, the "cue window" will appear on the sphere above, behind and to the left of the aircraft representation. This cues the pilot to take evasive action with respect to the threat at that location.
It is thus an object of the present invention to provide an improved craft situation indicator.